Pawpaw tree named ‘Aidfievate’

ABSTRACT

Disclosed herein is a new and distinct variety of pawpaw tree, which has been given the name ‘Aidfievate.’ This variety is distinguished by good yields (atypical of pawpaw), by excellent harvesting characteristics and by good fruit quality. The leaf aspect is unique among pawpaws, being horizontal rather than drooping, which allows fruit to be more easily seen and picked. Fruit display a dependable, readily visible color break at ripeness which speeds picking. The number of fruit per cluster is low, often in singles, which simplifies harvest. Fruit quality is high as fruit are medium to large in size with a low seed-to-fruit ratio, are very consistent in size and shape, and possess a very good flavor. Skin is medium-thick and fruit texture is firm which helps in shipping and handling. This variety is one of three varieties newly identified as having potential to establish a commercial pawpaw industry.

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinct and superior varietyof the pawpaw which is of interest for its fruit.

The species—Asimina triloba (L.) Dunal—is the largest native ediblefruit of North America, a member of the Annonaceae family, and thus arelative of the cherimoya, sweetsop, guanabana and custard apple (Annonacherimola, A. squamosa, A. muricata and A. reticulata), all of which arepopular fruits that are widely cultivated in tropical and subtropicalregions of the world, including southern Florida and southernCalifornia. The pawpaw is the only truly temperate member of theAnnonaceae, being indigenous to a region stretching from the Great Lakesto the Gulf Coastal Plain and from the Chesapeake Bay to the GreatPlains.

Currently, the pawpaw is considered to be semi-domesticated. NativeAmericans casually cultivated the tree, as did the white settlers whodisplaced them. The selection, propagation and naming of pawpawvarieties from the wild has been practiced for more than a century, andthe backyard cultivation of pawpaws for personal use is not uncommon inAppalachia and parts of the Midwest. Numerous unregistered, unpatentedvarieties are available in the mail-order nursery trade.

Commercial cultivation of pawpaw has not developed, however. The fruitis fragile and highly perishable which makes transport difficult. Andscientific attention towards improving the fruit, its culture and itspostharvest handling has received little attention until recently. Thelack of high quality cultivars that meet the requirements of producersand consumers is the foremost reason that commercial cultivation has notbeen undertaken.

The present invention, named ‘Aidfievate’ by the developer, is thesecond of three new and distinct varieties of pawpaw, each of whichrepresents a great improvement over existing pawpaw varieties because ofhigher yields, superior flavor, fewer seeds and firmer flesh. The othertwo varieties are ‘Wansevwan’, which is the subject of co-pendingapplication Ser. No. 09/954,536, and ‘Levfiv’, which is the subject ofco-pending application Ser. No. 09/954,186. These varieties possess theminimum overall qualities required for the development of a commercialpawpaw industry. The primary use of this pawpaw variety will be forfresh eating as a dessert fruit. Secondary use will be in processedproducts such as ice cream, yogurt, juice and cosmetics. Of the three,the variety ‘Aidfievate’ is outstanding for ease of harvest, and forconsistency of size and shape.

ORIGIN

The variety ‘Aidfievate’ was developed by R. Neal Peterson as the resultof a breeding project to improve the pawpaw, which he began in 1980. Theproject was conducted during a period when Peterson was employed as aneconomist with the Economic Research Service of the United StatesDepartment of Agriculture in Washington, D.C. However, because Petersonwas not employed in any capacity as a horticulturist or other researcherin the biological sciences, and no Department of Agriculture plantstock, facilities or information was used, the United States governmenthas no interest in the rights to the claimed variety.

The germplasm for Peterson's breeding project came principally from thesurviving remnants of five historic collections of pawpaw dating to theearly twentieth century that were the work of the most prominent pawpawcollectors and breeders of the time, and whose named material was nolonger propagated or otherwise available. In 1982 germ plasm(open-pollinated seed) was collected from these remnants and includedwith open-pollinated seed from named cultivars, which became the germplasm for his own breeding and selection work.

In 1983 the seed was germinated and in the following spring 808accessions were planted at the University of Maryland experimentstation, the Wye Research & Education Center, Queenstown, Md. Sincethen, the orchard has been supervised by the inventor, with basic staffsupport from the university. Basic tasks such as fertilizing, sprayingand mowing were conducted by the station staff. The inventor pruned,weeded, and collected data on growth rates, flowering, fruit set,yields, cluster size, fruit size and fruit quality, including data fromtaste panels which he organized.

In 1991, the inventor analyzed four years of data, and concluded inidentifying eleven trees as superior for further study. Nine of theseare involved in regional variety trials around the country and have beentermed advanced numbered selections. After nine additional years ofobservation, the original nine were narrowed to three that wereconsistently of the highest quality. One of these bears the accessionnumber PPF 8-58 and is the variety that is the subject of thisapplication. The original tree PPF 8-58 is 18 years old. This newvariety, named ‘Aidfievate,’ originated as an open-pollinated seedlingfrom a pawpaw tree on the grounds of the Blandy Experimental Farm,Boyce, Va., which tree was given the label BEF-30 by the inventor.Pawpaw BEF-30 is believed to have been a cataloged accession of theBlandy Experimental Farm's collection of Asimina triloba (circa1922-1955) although records to support this contention are now missing.To our knowledge BEF-30 has never been asexually propagated.

ASEXUAL REPRODUCTION OF THE VARIETY

In 1994, Peterson began topworking the Wye orchard to his elevenadvanced numbered selections, plus named varieties. Topworking wasaccomplished using bark-inlay grafting and chip-budding. Grafting of‘Aidfievate’ was easy by either method, and gave a medium-highpercentage of success. Replicates of ‘Aidfievate’ now number more than15 at the Wye, having been propagated through successive cycles ofgrafting over seven years. The rootstock for these grafts were matureseedling pawpaw trees growing in the orchard, and were a portion of theoriginal accessions from 1983, described previously. Six grafted treesof ‘Aidfievate’ have now been in bearing since 1997 and demonstrate thatasexual reproduction of this new and distinct variety preserves thedesirable characteristics of the variety and establishes and stablytransmits those characteristics through successive propagation at theQueenstown location.

SUMMARY OF THE VARIETY

‘Aidfievate’ is outstanding in its ease of harvesting and excels invigor, yields, flavor, and small cluster size. The fruit is medium insize, on average 200 gm for well-pollinated fruit, and may exceed 280gm. It is usually borne in clusters of one, two or three fruits. Fruitsize and shape is relatively uniform and consistent as compared to mostpawpaws. Fruit shape is typically ovate to nearly round. Skin thicknessis medium-thin, slightly thicker than is typical for the species. Skincolor is pale green and glaucous, and at the stage for picking exhibitsa noticeable color-break as the skin becomes paler and more yellowish.This color break is reliable and can be easily discerned with practice.The composition of the fruit is moderately fleshy, as measured by theseed-to-fruit ratio. The size of seeds is medium. The aroma of the fruitbefore and after cutting is pleasant and quite mild. The flavor is verygood, though not as good as ‘Wansevwan’—mild, sweet, free of bitternessor astringency, with a pleasant aftertaste. The pungent asiminouscomponent that is uniquely pawpaw and that many people findobjectionable is weak to absent. The flesh is firmer than average andvery smooth with no detectable fiber or grit, although a certainrubberiness in texture sometimes detracts from an otherwise pleasantmouth-feel. Fruit cracking is a problem on vigorous rootstocks. Theripening period at Queenstown has been mid-season, September 6 to 14,more or less, depending on the degree of heat in the preceding months.

Several non-fruit characters also serve to distinguish ‘Aidfievate’ fromother pawpaws. The aspect of the leaf in full sun is horizontal, acharacter that is unique to this variety and that contrasts with thetypical drooping aspect of pawpaw leaves. This horizontal leaf aspectallows for easy inspection of the tree's interior where the fruitdevelops, and this simplifies picking. The branching habit is morevertical than is typical of the species. Flower measurements when takenas a whole may also identify ‘Aidfievate.’ Its flower is borne on alonger peduncle than average, is larger than average, and is moreloosely closed in the female stage than is typical for pawpaw. For exactdata, see the detailed description and accompanying photographs.

This variety is susceptible to Talponia plummeriana, the pawpaw pedunclemoth, is susceptible to Eurytides marcellus, the zebra swallowtailbutterfly, and is believed to be susceptible to pawpaw decline disease,the same in all cases as the species. This variety responds veryvigorously to pruning and is difficult to control in size with pruningalone. It should be grafted onto less vigorous rootstocks both tocontrol ultimate tree size and to correct the tendency towards fruitcracking.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, leaves, flowers, fruits and seeds areshown in color that is as nearly true as is reasonably possible to makein color photographs of this nature. The deep maroon hues of the flowersare the most difficult for photoemulsions to render accurately.

FIG. 1 Shows the fruit of the new variety, hanging on the tree.

FIG. 2 Shows the fruit of the new variety in dissection, revealing thecolor, fleshiness and seeds.

FIG. 3 Shows the flower of the new variety in the female stage, inprofile and dissection.

FIG. 4 Shows the flowers of the new variety in the male stage, inprofile and dissection.

FIG. 5 Shows the habit of a pruned tree of the new variety.

FIG. 6 Shows a close-up of the leaves of the new variety.

BOTANICAL DESCRIPTION

Because no variety of Asimina triloba has had application made to thePatent Office, we include a botanical description of the species drawnfrom two taxonomic authorities, C. S. Sargent and R. Kral.

Shrub or small tree 1.5-11 (˜14) m tall from a stout, sometimes branchedtaproot, with a straight trunk seldom exceeding 30 cm in diameter; thebark of older trees gray-brown, shallowly furrowed, and marked withlarge ash-colored blotches; that of new shoots moderately to copiouslydark brown-hairy toward the summit, aging smooth, gray-brown; wintervegetative buds naked, without stipules, acuminate and dark brown torusty brown-hairy, 2-5 mm long, and tightly appressed against the stem;winter flower buds globose, dark brown-hairy, 2.5-5 mm in diameter;leaves membranaceous, oblong-obovate to oblanceolate, 15-30 cm long;apex acute to acuminate; base more or less gradually attenuate to theshort (0.5-1 cm) petiole; margin flat or scarcely revolute; youngsurfaces sparsely appressed reddish-pubescent above; densely so beneath,becoming glabrous above and sparsely hairy on the veins beneath; flowersgreen initially, then turning brown to maroon to deep vinous red, 2-5 cmbroad with a faintly fetid aroma, on densely dark brown-hairy, noddingpeduncles 1-2.5cm long which develop from the axils of the prominentleaf scars; calyx 8-12 mm long, of three triangular-deltoid sepals whichare striate with brown hairs on the outside, glabrous within, outerpetals 1.5-2.5 cm long, oblong-elliptic, with ascending bases andslightly to conspicuously recurved tips, copiously appressed-hairy alongthe veins outside, glabrous and impressed-veiny within; inner petals ⅓-½the length of the outer, elliptic, saccate-based, recurved tipped,glabrate without, glabrous and impressed-veiny within, with a corrugatednectary zone usually of a lighter color; androecium globular, 0.5-1 cmbroad, pale green at anthesis; gynoecium of 3-10 fusiformappressed-red-hairy carpels; fruits oblong-cylindric, 5-15 cm long,yellow-green to brownish when ripe, attached obliquely to the enlargedtorus of the peduncle in clusters of variable number; seeds 1.5-2.5 cmlong, brown to castaneous, shiny when mature, bean-shaped, somewhatlaterally compressed, contained within an aril that is confluent withthe pericarp from which the seed readily separates.

DETAILED DESCRIPTION OF THE INVENTION

Following is a detailed description of the new variety of pawpaw treewith color terminology in accordance with The Royal Horticulture Society(R.H.S.) Colour Chart (Ed. No. 2, 1986) except where general color termsof ordinary dictionary significance are used.

Tree:

Size.—Medium. 4.2 m on its own roots but taller on more vigorousrootstock.

Vigor.—High. Approximately 62 cm growth on strong primary laterals understandard fertilization of 50 lbs of N per acre.

Habit.—Rounded with age whether pruned or unpruned.

Branching pattern.—Vertical and spreading with time. Crotch angles varyfrom narrow to wide. Branch spacing varies from widely to closelyspaced.

Apical dominance.—High.

Trunk.—Diameter 13.4 cm measured at 30 cm above ground level.

Bark.—Smooth with small raised horizontal lenticels, typical of thespecies. Color between R.H.S. Greyed-Green 197B and Grey 201B on bothtrunk and branches.

Leaf buds:

Length.—Axillary buds growing on branches of normal vigor are small, 2.1mm average with a range of 1.5 to 2.6 mm. Buds growing on branches ofhigh vigor larger, 2.7 mm average with a range of 2.5 to 2.9 mm.

Leaves:

Shape.—Oblanceolate with acuminate tip and attenuate to the base, as istypical for the species. Average ratio of width to length is 0.444.

Size.—Measurements are from mature leaves attached at midpoint ofactively growing shoots of current season's growth. Size is 10.4 cmwide, 23.8 cm long.

Color.—Upper surface R.H.S. Green 147A. Lower surface R.H.S.Yellow-Green 146A. Both colors typical for the species.

Aspect.—Horizontal or nearly so. Leaves on the vertical shoots of theupper portion of the tree curled in a strongly concave fashion. Bothfeatures very atypical of the species.

Margin.—Entire, and slightly undulating which is atypical of thespecies.

Texture.—Smooth to only slightly impressed veiny, typical for thespecies.

Arrangement.—Alternate opposite.

Petiole.—Color yellow-green similar to lower leaf surface. Averagediameter 3.3 mm at the petiole midpoint. Length ranges from 16.7 to 18.9mm with an average of 17.9 mm. NOTE: The structure of the pawpaw leaflamina is such, in the way that it tapers gradually to the petiole, thatvisual demarcation of the petiole terminus is imprecise and theresultant measurement of petiole length has a high margin of error. Themeasurements reported here are based on a precise tactile method. Bymeans of running the back of one's thumbnail down the midvein (on theunderside of the leaf) towards the petiole one encounters a suddenchange in curvature, diameter, and hardness. This point of change is thepetiole terminus and is easy to detect and replicate.

Flower buds:

Size.—Length 4.9 mm average. Width 3.6 mm average.

Appearance.—Very dark brown, between R.H.S. Brown 200A and Black 202A.Surface densely pubescent, velvety.

Flower:

Size.—Large. As the flower matures from female to male stage, the petalsreflex, and therefore measured flower size is specific to flower stage,which data are presented below.

Outer petals.—Average of 28 mm wide, 35 mm long. Average ratio of widthto length 0.80.

Inner petals.—Average of 11 mm wide, 19 mm long. Average ratio of widthto length 0.58.

Color.—Maroon.

Form of female stage flower.—More loosely closed than typical.

Size of the female stage flower.—Diameter 40 mm average.

Nectary band of female stage flower.—Reddish-maroon color, not as darkas surrounding inner petal.

Form of male stage flower.—Outer and inner petals flaring and recurved,in typical fashion for the species.

Size of the male stage flower.—Diameter 53 mm average.

Nectary band of male stage flower.—A deep maroon color, basicallyindistinguishable from the inner petal color.

Peduncle.—Average length 20 mm. Lightly pubescent with brown hairs.

Fruit:

Dates of picking.—Mid-season, generally from September 5 to 14 atQueenstown, but dates can vary by more than a week depending on degreeof summer heat.

Cluster size.—Few fruited. One, two and three-fruited clusters are mostprevalent, and this small cluster size is atypical of pawpaw. Largerclusters also occur. Fruit tends towards a uniform size, atypical of thespecies.

Fruit shape.—Ovate to nearly round. Shape varies considerably; but largewell-formed fruit in single-fruited cluster tend towardslength-to-width-to-depth proportions of 100:70:70.

Fruit size.—Medium, 200 gm average for well-pollinated fruit. Largerthan typical pawpaw. Size varies from small (˜23 gm) to large (˜280 gm),dependent on the number of fertilized seed present in the fruit. Lengthsnormally range 4.4-10.8 cm, widths 3.1-7.6 cm, and depths 3.1-7.6 cm.

Suture.—Typically absent to indistinct.

Abscission type.—Primary mode is for peduncle to abscise from the branchremaining attached to the fruit (for single-fruited clusters).Abscission may also occur at the point of peduncle attachment to thefruit.

Abscission scar.—Medium, 9.2 mm in diameter. A character of lowvariance.

Peduncle.—Length 24.3 mm on average, ranging from 21.0 to 29.0 mm.Diameter extremely variable, varying in proportion to the cluster fruitmass, as is typical of the species. In comparison to the range ofpeduncle sizes of pawpaw cultivars, and relative to the total clusterfruit weight, the diameter is medium. Peduncle pubescence rufus, mediumdensity. The point of peduncle attachment to single-fruited clusters isaligned with the central axis of the fruit, or only slightly offset tothe dorsal side.

Skin color.—Under-ripe fruit pale green and glaucous, R.H.S.Yellow-Green 146D. Ripe fruit pale yellowish green and glaucous, R.H.S.Yellow-Green 151A. After the fruit passes its climacteric peak and fallsfrom the tree, brown blotches appear which spread to cover the entireskin surface, as is typical for the species.

Color break.—Subtle but reliable color change at the time when the fruitmay be picked. Exact color change noted in preceding paragraph.

Skin thickness.—Medium-thick.

Aril.—Thin, tender, and edible.

Fleshiness.—Moderately high. Percent seed is 5.7 on average. The averagequantity of pulp per seed is 19.3 gm.

Flesh color.—Creamy yellow and uniform throughout. Color ranges fromR.H.S. Yellow 13C to Yellow-Orange 15C.

Aroma of uncut fruit.—Pleasant. Low power.

Aroma of cut fruit.—Pleasant. Low power.

Flavor.—Very sweet, Brix 19%, mild, nonbitter, and nonastrigent. Pungentasiminous component low to absent.

Aftertaste.—Pleasant, long lingering, no negative components.

Consistency.—Pleasant mouth-feel. Flesh is firm (atypical of pawpaw) andsmooth but sometimes with a slightly rubbery texture. No detectablefiber or grit.

Use.—Principally for fresh eating as a dessert fruit. Secondarily inprocessed products.

Seed:

Size.—Medium. 1.33 gm average weight. Dimensions 25.2 mm long, 14.0 mmwide, 7.1 thick on average.

Color.—Dark brown. R.H.S. Brown 200A.

Number per fruit.—9 per average fruit of 210 gm. As fruit size variesgreatly in pawpaw, the seed number per fruit is not a stable character,unlike the seed-to-fruit ratio (percent seed) which is stable.

Physiological and ecological characters:

Graftability.—Very easy to graft by virtually all methods. Percent takeis medium to high for pawpaw, in vicinity of 85-95%.

Habit of tree after grafting.—Vigorous. Time to flowering on establishedrootstock is roughly three years. It appears that common seedlingrootstocks have more vigor than the tree's own roots.

Pruning.—The tree responds vigorously to pruning, sometimes with toomuch vegetative vigor, depending on rootstock. Flowering and generalvigor increased by pruning.

Flower count.—Medium to high. Average of 5.3 blossoms per branch onvigorous branches, but flower number varies considerably depending onthe vigor of the branch.

Self-fruitfulness.—Requires cross pollination.

Bearing.—Annual and consistent.

Fruit set.—Low, less than 20 percent in most years.

Yields.—High. From mature trees approximately 30 lbs. of fruit per tree.At orchard densities of 330 trees per acre, this is 10,000 lbs per acre.

Keeping quality of fruit (normal storage, 24° C.).—Short. Three dayswhen ripe. Typical for the species.

Keeping quality of fruit (cold storage, 2° C.).—Moderate. Three weekswhen picked at the proper stage of color break.

Shipping quality of fruit.—Medium if shipped refrigerated with adequatecushioning. Poor otherwise because of the rapid ripening which istypical for pawpaw.

Drought and heat tolerance.—Good, similar to the species. Droughttolerance superior to peach.

Hardiness.—Fully hardy at Queenstown location, USDA Zone 7. Believedhardy to Zone 5 (average annual minimum temperature −30° C.), the sameas for the species.

Resistance to Talponia plummeriana.—Susceptible.

Resistance to Eurytides marcellus.—Susceptible.

Resistance to pawpaw decline disease.—Believed to be susceptible.

Variance in botanical details: The pawpaw tree and its fruit describedherein will vary due to climate, soils, growing conditions and culture.

I claim:
 1. A new and distinct variety of pawpaw tree obtained as anopen-pollinated seedling of BEF-30 (unpatented), substantially as shownand described herein.